Browsing by Author "Rojas Henríquez, Felipe Ignacio"

Now showing 1 - 3 of 3
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    Depthwise convolutional neural network for multiband automatic quasars classification in ATLAS
    (2023) San Martín Jiménez, Astrid Elizabeth; Pichara Baksai, Karim Elías; Barrientos, Luis Felipe; Rojas Henríquez, Felipe Ignacio; Moya Sierralta, Cristóbal Andrés
    In recent years, the astronomical scientific community has made significant efforts to automate quasars' detection. Automatic classification of these objects is challenging since they are very distant and appear as point sources, outnumbered by other sources. Thus, performing automatic morphological classification is not straightforward; colour dimension seems better as a key concept. Previous work using machine learning tools has proposed classifiers that use features such as magnitude and colour, working only for quasar representation, which requires high-quality observational data that is not always available. Those features are computationally costly in extensive image surveys like VST ATLAS (Shanks et al. 2015). With the continuous developments in deep-learning architectures, we find a powerful tool to perform automatic classification from images, where capturing information from different bands takes relevance in this kind of approach. In this work, we developed a new quasar selection method that we hope to apply to the complete ATLAS survey in subsequent papers, where the completeness and efficiency of depthwise architecture will be compared to more standard methods such as selection on the colour-colour diagrams and machine-learning feature-based methods. This automatic quasar classification tool uses images in u, g, i, z bands available in ATLAS, heading towards new survey requirements facing the big data era. We propose a deep-learning architecture based on depthwise convolutional units that work directly with ATLAS images, reduced by the VST pipeline. Our model reaches an accuracy of 96.53 per cent with a quasar classification f1-score of 96.49 per cent, a very competitive benchmark compared to previous unscalable approaches....
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    Discovery and characterization of exoplanets in the TESS full frame images
    (2022) Rojas Henríquez, Felipe Ignacio; Jordán Colzani, Andrés Cristóbal; Chanamé, Julio; Pontificia Universidad Católica de Chile. Instituto de Astrofísica
    En los últimos años la cantidad de exoplanetas ha ido en aumento. Hoy conocemos más de 5000 y este numero seguirá creciendo gracias a misiones como TESS, que monitorea constantemente estrellas cercanas desde el espacio. No obstante, de todos estos planetas descubiertos, menos de 1000 tienen mediciones de su masa y radio con una precisión del 20% o mejor. Conocer estos parámetros con precisión nos da una idea inicial de su composición y por ende, de cómo pudo haber sido su proceso de formación. Además, se conocen muy pocos planetas gigantes con órbitas con períodos superior a los 10 días. Este tipo de planetas (Gigantes Tibios) despiertan la pregunta de cómo es que se encuentran tan cerca de la estrella que orbitan. Al mismo tiempo, estos conservan posibles rastros de su evolución dinámica en sus órbitas, a diferencia de planetas con órbitas más pequeñas. El objetivo de este proyecto es implementar un sistema de procesamiento de las imágenes de la misión TESS y búsqueda de planetas gigantes tibios, en el marco de la colaboración WINE, dedicada al estudio de estos planetas. De los candidatos a planeta encontrados, se realizó el seguimiento, confirmación y caracterización de un Neptuno (TOI-883 b) y un sub-Saturno (TOI-899 b), que orbitan estrellas muy parecidas al Sol con períodos de 10 y 12 días, respectivamente.
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    TOI-954 b and K2-329 b: Short-period Saturn-mass Planets that Test whether Irradiation Leads to Inflation
    (2021) Sha, LZ; Huang, CLX; Shporer, A; Rodriguez, JE; Vanderburg, A; Brahm, R; Hagelberg, J; Matthews, EC; Ziegler, C; Livingston, JH; Stassun, KG; Wright, DJ; Crane, JD; Espinoza, N; Bouchy, F; Bakos, GA; Collins, KA; Zhou, GR; Bieryla, A; Hartman, JD; Wittenmyer, RA; Nielsen, LD; Plavchan, P; Bayliss, D; Sarkis, P; Tan, TG; Cloutier, R; Mancini, L; Jordan, A; Wang, SR; Henning, T; Narita, N; Penev, K; Teske, JK; Kane, SR; Mann, AW; Addison, BC; Tamura, M; Horner, J; Barbieri, M; Burt, JA; Diaz, MR; Crossfield, IJM; Dragomir, D; Drass, H; Feinstein, AD; Zhang, H; Hart, R; Kielkopf, JF; Jensen, ELN; Montet, BT; Ottoni, G; Schwarz, RP; Rojas Henríquez, Felipe Ignacio; Nespral, D; Torres Miranda, Pascal Jose; Mengel, MW; Udry, S; Zapata, A; Snoddy, E; Okumura, J; Ricker, GR; Vanderspek, RK; Latham, DW; Winn, JN; Seager, S; Jenkins, JM; Colon, KD; Henze, CE; Krishnamurthy, A; Ting, EB; Vezie, M; Villanueva, S
    We report the discovery of two short-period Saturn-mass planets, one transiting the G subgiant TOI-954 (TIC 44792534, V = 10.343, T = 9.78) observed in TESS sectors 4 and 5 and one transiting the G dwarf K2-329 (EPIC 246193072, V = 12.70, K = 10.67) observed in K2 campaigns 12 and 19. We confirm and characterize these two planets with a variety of ground-based archival and follow-up observations, including photometry, reconnaissance spectroscopy, precise radial velocity, and high-resolution imaging. Combining all available data, we find that TOI-954 b has a radius of 0.852(-0.062)(+0.053) R-J and a mass of 0.174(-0.017)(+0.018) M-J and is in a 3.68 day orbit, while K2-329 b has a radius of 0.774(-0.024)(+0.026) R-J and a mass if 0.260(-0.022)(+0.020) M-J and is in a 12.46 day orbit. As TOI-954 b is 30 times more irradiated than K2-329 b but more or less the same size, these two planets provide an opportunity to test whether irradiation leads to inflation of Saturn-mass planets and contribute to future comparative studies that explore Saturn-mass planets at contrasting points in their lifetimes.